Micro-fabrication Employing UV Microstereolithography

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2 Materials Opportunities on Layered Manufacturing Technology 2 (MOLMT-2) Micro-fabrication Employing UV Microstereolithography Professor Chris Chatwin, Dr R.C.D.Young, Dr D. Budgett, Phil Birch University of Sussex, UK Organised by Professor Brian Derby Manchester Materials Science Centre, UMIST; June 3 rd 6 th , Weston Conference Centre, UMIST, Manchester, UK

3 Fabrication of high aspect ratio 3D micro-components Develop a new microstereolithography technique that operates in the UV and Visible part of the spectrum Manufacture micro-components which are complex in shape and have micron resolution

4 Lithography Existing Technologies for MicroFabrication Components constructed by superimposing a limited number of thin film layers or by using deep UV lithography. Permits only limited complexity in the third dimension.

5 Meshing gears on a moveable platform. A laminated comb actuator results in nearly five times the electrostatic force of a single level actuator. Grain of pollen and red blood cells

6 I x I 1 mcos kx 0

7 Cibatool SL 5180 and Somos 6100 Experimental Conditions: Sample Thickness =100 m Temperature 19 ºC Relative Humidity % Cibatool SL 5180:non-viscous, good quality samples Somos 6100: viscous, suffers from bubble trapping that causes scattering (%) Diffraction efficiency Ciba-Geigy Cibatool SL DuPont Somos Grating spacing ( m) 30 Normalized diffraction efficiency (%) Time (sec) Ciba-Geigy Cibatool SL 5180 DuPont Somos 6100 (%) DuPont Somos Grating Spacing ( m)

8 Delay Rate Delay time (ms) Ciba-Geigy Cibatool SL 5180 DuPont Somos 6100 diffraction build-up rate (%/ms) Ciba-Geigy Cibatool SL 5180 DuPont Somos Irradiance (W/cm 2 ) irradiance (W/cm 2 ) delay (ms) DuPont Somos 7100 diffraction build-up rate (% / DuPont Somos irradiance (W/cm 2 ) irradiance (W /cm 2 )

9 STL Interface

10 Slices from STL Model

11 I/O Interfacing (AT-MIO-16DE-10) Encoder driver Card ( ) Encoder Module Shutter SLM Microstereolithography System Diagram Experimental Set-up UV LASER (351 or 363nm) (7) D.O.E Slice Images Polarizer lens Sync. T132 Shutter controller RS-232 (0.1ms resolution) (15) Frame Grab (Ultra-II drive) Parallel I/O Ports (PC-DIO-10) Interface of data acquisition Translation Stage Serial DDI SunSparc IBM PC (6) -component (DUCT CAD/CAM) (Main control) Resin Bath Network (ftp) or GPIB Interfacing

12 Basic Control Process Vision system to observe the condition of the cured - component 6 Move translation stage for re-coating 5 1 Process Control PC - Windows NT measurement and control of position send an image slice to SLM Shutter OFF shutter ON for laser beam exposure

13 Translation Stage Features 20nm resolution 0.1 m accuracy 50mm travel range DC servo motor PID feedback contol with encoder actuator Gearhead ratio of 485:1

14 Spatial Light Modulator (SLM) SVGA SLM 800x600 pixels Features VGA and SVGA Ultra-II PCI Frame Grab with video and VGA frame buffers (2Mb each) CCIR/PAL camera Overlay display

15 Twisted Nematic Liquid Crystal

16 Reduction Lens and Photo-polymer Bath

17 Main Programme Control Panel

18 Interface Control Micro-SLA System Resin Bath Lithographic Lens

19 Micro- SLA System

20 MicroSLA System

21 A micro-gear (50 micron layers)

22 A case for a micro-motor (50 micron layers)

23 A helix (50 micron layers)

24 A double helix (50 micron layers)

25 A micro-pyramid (35 micron layers)

26 Micro-pyramid (50 micron layers)

27 Detail of the centre of a micro pyramid (25 layers of 50 microns each)

28 A micro-wheel (5 micron layers)

29 Photopolymer Rapid Opto-electronic Manufacture of Macro/micro Prototype Products BRITE-EURAM Monomer: hexane-dioldiacrylate (HDDA) Photoinitiators: Igracure 651 (DMPA) absorbs nm Igracure 819 absorbs up to 450 nm 50 mj/cm 2 for 100 m cure depths, resolution of 40 m Alumina (Al ) Powder: Average diameter 0.5 m; Refractive index 1.7

30 Photopolymer Rapid Opto-electronic Manufacture of Macro/micro Prototype Products BRITE-EURAM Mask Cured at 365 nm with Hg Lamp Ceramic parts produced with visible source and CRL XGA mask 8mm x 8mm 120 micron thick polymerised layer, resolution 50 microns; 80 wt% alumina, 0.5 wt% DMPA wrt HDDA monomer

31 Micromachining - Electronics & Sensors Lambda Physik LPX 201i, 125W mean power, 2.5J/pulse,100 Hz prf, 10 to 50 ns pulse width Micro-fluidic systems Chrome on Quartz Mask

32 References 1) C Chatwin, M Farsari, S Huang, M Heywood, P Birch, R Young, UV microstereolithography system that uses spatial light modulator technology, Applied optics 37 (32), , ) M Farsari, S Huang, RCD Young, MI Heywood, PJB Morrell, CR Chatwin, Holographic characterization of epoxy resins at nm, Optical Engineering 37 (10), , ) M Farsari, S Huang, RCD Young, MI Heywood, PJB Morrell, CR Chatwin, Four-wave mixing studies of UV curable resins for microstereolithography, Journal of Photochemistry and Photobiology A: Chemistry 115 (1), 81-87, ) M Farsari, S Huang, P Birch, F Claret-Tournier, R Young, D Budgett, Microfabrication by use of a spatial light modulator in the ultraviolet: experimental results, optics letters 24 (8), , ) CR Chatwin, M Farsari, S Huang, MI Heywood, RCD Young, PM Birch, Characterisation of epoxy resins for microstereolithographic rapid prototyping, The International Journal of Advanced Manufacturing Technology 15 (4), , ) GD Ward, IA Watson, DES Stewart Tull, AC Wardlaw, CR Chatwin, Inactivation of bacteria and yeasts on agar surfaces with high power Nd: YAG laser light, Letters in applied microbiology 23 (3), , ) M Farsari, S Huang, RCD Young, MI Heywood, CD Bradfield, CR Chatwin, Holographic cure monitoring of the DuPont Somos TM 7100 stereolithography resin, Optics and lasers in engineering 31 (3), , ) M Farsari, F Claret-Tournier, S Huang, CR Chatwin, DM Budgett, A novel high-accuracy microstereolithography method employing an adaptive electro-optic mask, Journal of Materials processing technology 107 (1), , ) P Birch, R Young, C Chatwin, M Farsari, D Budgett, J Richardson, Fully complex optical modulation with an analogue ferroelectric liquid crystal spatial light modulator, Optics communications 175 (4), , ) PM Birch, R Young, D Budgett, C Chatwin, Two-pixel computer-generated hologram with a zero-twist nematic liquid-crystal spatial light modulator, Optics letters 25 (14), , ) P Birch, R Young, M Farsari, C Chatwin, D Budgett, A comparison of the iterative Fourier transform method and evolutionary algorithms for the design of diffractive optical elements, Optics and Lasers in engineering 33 (6), , ) P Birch, R Young, D Budgett, C Chatwin, Dynamic complex wave-front modulation with an analog spatial light modulator, Optics letters 26 (12), , 2001

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